^^ This. If the OD of the dummy suppressor matched the ID of your intended suppressor tubing, you could use the 1st .75-1" for the muzzle mount. Turn some grooves in the fake suppressor then do a roll crimp on the outside tubing to lock it in. You'd still be stuck with aluminum mounting threads which may be less than ideal.
I'm kind of thinking this. It will be (if i ever do anything with this) a scrap metal/spare junk suppressor made of old washers, motor valves or tubing.
I like the idea of using 2 diameters for the can. Maybe just use the first inch then expand out to another piece of tubing .5 to .75 inches wider in diameter. Definitly not a tactical masterpiece, but a fun grouse hunting/ bluejay removing pistol.